java反射代理学习

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Arrays;


public class ReflectTest {


static class Type{


public int pubIntField;
public String pubStringField;
private int prvIntField;


public Type(){
Log("Default Constructor");
}


Type(int arg1, String arg2){
pubIntField = arg1;
pubStringField = arg2;


Log("Constructor with parameters");
}



public int getPrvIntField() {
return prvIntField;
}


public void setPrvIntField(int prvIntField) {
this.prvIntField = prvIntField;
}


private void Log(String msg){
System.out.println("Type:" + msg);
}


}


static class ExtendType extends Type{

public int pubIntExtendField;
public String pubStringExtendField;
private int prvIntExtendField;


public ExtendType(){
Log("Default Constructor");
}


ExtendType(int arg1, String arg2){
pubIntExtendField = arg1;
pubStringExtendField = arg2;


Log("Constructor with parameters");
}


public void setIntExtendField(int field7) {
this.prvIntExtendField = field7;
}


public int getIntExtendField() {
return prvIntExtendField;
}


private void Log(String msg){
System.out.println("ExtendType:" + msg);
}


}


public static void testClassInstance(){

Boolean foo = true;

Class obj1 = foo.getClass();
Class obj2 = Boolean.class;
Class obj3 = Boolean.TYPE;
try {
Class obj4 =Class.forName("java.lang.Boolean");
System.out.println(obj4);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(obj1);
System.out.println(obj2);
System.out.println(obj3);

}

public static void testGetFields(){

/*可见getFields和getDeclaredFields区别：
getFields返回的是申明为public的属性，包括父类中定义，
getDeclaredFields返回的是指定类定义的所有定义的属性，不包括父类的。*/

Class classType = ReflectTest.ExtendType.class;
System.out.println(classType);
// 使用getFields获取属性


Field[] fields = classType.getFields();
for (Field f : fields){
System.out.println(f);
}

System.out.println("+++++");
// 使用getDeclaredFields获取属性
fields = classType.getDeclaredFields();


for (Field f : fields){
System.out.println(f);
}
}

public static void testGetMethods(){
Class classType = ExtendType.class;
Method[] methods = classType.getMethods();
for (Method m : methods){
System.out.println(m);
}


System.out.println("======");
methods = classType.getDeclaredMethods();


for (Method m : methods){
System.out.println(m);
}
}

public static void testGetConstructos(){
// 使用getConstructors获取构造器
Class classType = ExtendType.class;
Constructor[] constructors = classType.getConstructors();
for (Constructor m : constructors){
System.out.println(m);
}


System.out.println();


// 使用getDeclaredConstructors获取构造器
constructors = classType.getDeclaredConstructors();
for (Constructor m : constructors){
System.out.println(m);
}
}

public static void testNewInstance(){
Class classType = ExtendType.class;
Object inst1 = null;
Object inst2 = null;
Object inst3 = null;
try {
inst1 = classType.newInstance();
} catch (InstantiationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

Constructor constructor1 = null;
Constructor constructor2 = null;
try {
constructor1 = classType.getConstructor();
constructor2 = classType.getDeclaredConstructor(int.class, String.class);
} catch (SecurityException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchMethodException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
inst2 = constructor1.newInstance();
inst3 = constructor2.newInstance(1, "123");
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InstantiationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(inst1);
System.out.println(inst2);
System.out.println(inst3);
}

public static void testInvokeMethods(){
Class classType = ExtendType.class;

Object inst = null;
try {
inst = classType.newInstance();
} catch (InstantiationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

Method logMethod = null;
try {
logMethod = classType.getDeclaredMethod("Log", String.class);
} catch (SecurityException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchMethodException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
logMethod.setAccessible(true);//不加这句，报private异常，
logMethod.invoke(inst, "test");
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}

public static void testGetterAndSetter(){
Class classType = ExtendType.class;


Object inst = null;
try {
inst = classType.newInstance();
} catch (InstantiationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}


Field intField = null;
try {
intField = classType.getField("pubIntExtendField");
} catch (SecurityException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchFieldException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}


try {
intField.setInt(inst, 100);
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

try {
int value = intField.getInt(inst);
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}


testSetter(classType, inst, "prvIntField", 10);
System.out.println(testGetter(classType, inst, "prvIntField"));
}
public static Object testGetter(Class classType , Object obj, String fieldName){

return testAccessField(classType, obj, fieldName, null, false);

}
public static void testSetter(Class classType , Object obj, String fieldName, Object fieldVal){

testAccessField(classType, obj, fieldName, fieldVal, true);
}

private static Object testAccessField(Class classType , Object obj, String fieldName, Object fieldVal,boolean flag){
Object fieldObj = null;

Method[] methods = classType.getMethods();
Method getMethod = null;
Method setMethod = null;
for (int i = 0; i < methods.length; i++) {
System.out.println(methods[i].getName());
String methodName = fieldName.substring(0,1).toUpperCase()+fieldName.substring(1);

if(flag){
if(("set"+methodName).equals(methods[i].getName())){
setMethod = methods[i]; break;
}
}else {
if(("get"+methodName).equals(methods[i].getName())){
getMethod = methods[i]; break;
}
}
}

try {
if(flag){
if(setMethod != null){
setMethod.setAccessible(true);
setMethod.invoke(obj, fieldVal);
}else{
//field.set(obj, fieldVal);
System.err.println("error");
}
}else{
if(getMethod != null){
getMethod.setAccessible(true);
fieldObj = getMethod.invoke(obj);
}else{
//fieldObj =field.get(obj);
System.err.println("error");
}
}

} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return fieldObj;
}

public static void testGetterAndSetter(Class classType , Object obj, String fieldName, Object fieldVal){

Object fieldObj = null;
/*Field[] fields = classType.getFields();

Field field = null;

for (int i = 0; i < fields.length; i++) {
if( fieldName == fields[i].getName()){
field = fields[i];
break;
}
}

if(field == null){ return ;}*/

Method[] methods = classType.getMethods();
Method getMethod = null;
Method setMethod = null;
for (int i = 0; i < methods.length; i++) {
System.out.println(methods[i].getName());
String methodName = fieldName.substring(0,1).toUpperCase()+fieldName.substring(1);
if(("get"+methodName).equals(methods[i].getName())){
getMethod = methods[i];
continue;
}
if(("set"+methodName).equals(methods[i].getName())){
setMethod = methods[i];
continue;
}
if(getMethod != null && setMethod != null) break;
}


try {

if(setMethod != null){
setMethod.setAccessible(true);
setMethod.invoke(obj, fieldVal);
}else{
//field.set(obj, fieldVal);
System.err.println("error");
}

if(getMethod != null){
setMethod.setAccessible(true);
fieldObj = getMethod.invoke(obj);
}else{
//fieldObj =field.get(obj);
System.err.println("error");
}



} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

System.out.println(fieldObj);

}

static interface Face{

public void say();

public int count();
}

static class RealTeller implements Face{


@Override
public void say() {
System.out.println("hello");
}


@Override
public int count() {
// TODO Auto-generated method stub
return 100;
}


}

static class CommonHandler implements InvocationHandler{

private Object target;

public CommonHandler(Object target){
this.target = target;
}


@Override
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
// TODO Auto-generated method stub
//System.out.println("proxy--"+proxy);
//System.out.println("target--"+target);
//System.out.println("Method:"+ method + ",Args:" + args);

return method.invoke(target, args);
}

}



public static Object testProxy( Object target){

//Face target = new RealTeller();
Object proxy = (Face) Proxy.newProxyInstance(ReflectTest.class.getClassLoader(),
target.getClass().getInterfaces() , new CommonHandler(target) );
return proxy;

}

public static void main(String[] args) {
//testClassInstance();
//testGetFields();
//testGetMethods();
//testGetConstructos();
//testNewInstance();
//testInvokeMethods();
//testGetterAndSetter();
Face face = (Face) testProxy(new RealTeller());
System.out.println(face.getClass());

face.say();

System.out.println(face.count());
}


}